Automatic screw thread lapping machine



Jan. 3,1950 A. M. DRAKE 2,493 3 AUTOMATIC S-GREW THREAD LAPPING MACHINE Filed July 13, 1946 i 2 Sheets-Sheet 1 INVENTOR. A'ldP/Z 1. fiimke W M W AYTORZVE V Jan. 3, 1950 A. M. DRAKE AUTOMATIC SCREW THREAD LAPPING MACHINE 2 Sheets-Sheet 2 my. 7 s

Filed July 13, 1946 INVENTOR. fl/delz 11X fire/ 49 Arm/gym mounted piston adapted to be reciprocated between adjustable limits, preferably by hydraulic means; seventh, a worm on the piston engaging a worm wheel on the inner end of the spindle so that vertical movements of the piston and its worm acting as a rack will oscillate the spindle; eighth, annular rack teeth on the piston meshing with a gear on an intermediate shaft connected byintermeshing gears with the sleeve so that vertical movements of the piston and rack will oscillate the sleeve; ninth, an elongated spur gear on the piston drivingly connected to a corresponding gear on the lower end of a vertical shaft; and tenth, suitable means for slowly,

preferably step by step, rotating this vertical shaft :to slowly rotate the'piston arid the lap carrying spindle. 1

Referring more in detail to the figures'of the drawings, there is shown in section in Fig. 1 a headstock I8 having rotatably mounted therein a sleeve member I2. At its forward or outer end there is a radially extending plate I4 having a: horizontally extending armv I5 detachably mounted thereon. As shown in Fig. 1, this sleeve I2 maybe rotated upon alined anti-friction'bearings I8 mounted within the headstock I0 adjacent its opposite ends so that it may oscillate,

as presently to be described, upon a horizontal axis. On the rear or inner end of the sleeve I2 is a spur gear in mesh with a corresponding spur gear 22 on an intermediate shaft also having formed'thereon a second gear 24 meshing with the annular teeth 25 of a circular rack portion on the vertical piston 28.

Mounted within the sleeve I2 and coaxial therewith on anti-friction bearings 38 therein is anism that vertical movements of the piston 28 will oscillate the spindle 32 by worm gear 38 meshing with worm 48 through an angle dependent upon the extent of vertical movement of the'piston 28. Simultaneously the sleeve I2 will also be oscillated through an angle dependent upon the ratio of its connecting gears 20, 22 and 24 and the vertical movements of the piston 28. Also by reason of the interposed pair of spur gears between the driving rack 26 and the sleeve I2 the direction of any oscillatory movement of the sleeve will always be in the opposite direction to the simultaneous oscillatory movement of the spindle 32. 7

Inorder to slowly rotate the spindle 32 so that the work piece W will engage portions of slightly increased diameter of the lapping tool during the progress of the lapping operation, means are provided to rotate the vertically actuated piston 28 preferably by a step ,bystep means. A small horizontally actuated piston, 42; is reciprocated hydraulically during oscillatory movements of the sleeve I2 and spindle 32 .byany desired means. This reciprocatory movement, by means of a pawl 44 carried by the piston, advancesa ratchet gear 48 on the rear end of'a shaft 48. This shaft 48 carries at its forward end a gear 58 intermeshing, as shown in Fig. .11, directly with a gear 52on the forward end of a horizontal shaft 54. On the rear end of shaft 54 is a bevel pinion 55 and this pinion meshes with agbevel gear .58 at the upper end of a vertical shaft 68 rotatably mounted within a portion of the headstock I8. At the lower end of this shaft 88 is a spur gear 62 meshing with an elongated spur gear 64 on the vertically actuated piston 28 so that this gear 64 is always in engagement with its companion gear during reciprocatory movements of this piston. The step-by-step rotation of shaft 48 by the ratchet 44 will thus slowly rotate shafts 54 and 60 and piston 28 in a step-by-step manner.

To reverse the direction of slow step-by-step rotation of the piston 28 so that the machine may be adapted for advancing either right or left hand threaded work pieces along the lapping tool 35, an alternative drive is provided between the ratchet gear 46 and the bevel pinion 58. For this purpose a third shaft or stud 56 is provided parallel to shafts 48 and 54. By gearing, there:- fore, from gear 5I on shaft 48 to a gear '55 on stud 65 and from the gear on stud 66 to a gear 5'! on shaft 54 rotation in opposite directions from the direct gearing between shafts 4B and 54 may be effected.

Slow step by step rotative movements are imparted to the piston 28 by the above-described mechanism. By the selection of the proper gearing between the pawl carrying piston 42 and the vertical shaft driven thereby the direction and amount of rotation of the vertical piston 28 can be reversed and limited to accommodate the machine for lapping left or right hand threads of different types and sizes. By changin the angular position of the work piece W within its holder 61 by rotation of the manually operated member 68 the advancing movement of the work piece W along lapping tool 36 can be speeded or retarded by the operator as required by the progress of the lapping of the particular work p1ece.

The pistons 28 and 42 are reciprocated by bydraulic elements and aredisposed in a hydraulic system similar to the means for actuating the spindle and work oscillating mechanism disclosed and claimed in my above referred to Patent No. 2,379,693. As these means form no part of the present invention, it will be unnecessary to describe them in detail. I

It will be understood that the piston 42 is slidable within its cylinder I0 and reciprocated by alternately admitting fluid under pressure :to its opposite ends. Similarly, the vertical piston 28 within alined cylinder portions I2 is similarly reciprocated as by means of suitable valves I4 and I5.

To control the length of oscillatory movements of the sleeve I2 and spindle 32, adjustable dogs I3 may be provided on the lower portion of the sleeve I2 for engagement by a control lever I5 within the hydraulic system of the machine. Reversals of movement of the vertical piston 28 and oscillatory movements of the sleeve I2 are eifected by contact with and operation of the control lever I5 by the dogs I3. For this purpose the control lever I5 is connected to an oscillating distributing valve I8 by means of which fluid under pressure in the hydraulic system is admitted to the cylinders for pistons 28 and 42.

I claim:

1. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatably mounted within said sleeve, a thread lapping tool on said spindle, means to oscillate said sleeve, means to oscillate said spindle simultaneously with said sleeve, means connecting said sleeve to a holder for the work piece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, and means to slowly advance said spindle rotatably during oscillations thereof.

2. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatably mounted within said sleeve, 3. thread lapping tool on said spindle, means to oscillate said sleeve, said means also oscillating said spindle simultaneously with said sleeve, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, and means to slowly advance said spindle rotatably during oscillations thereof.

3. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatably mounted within said sleeve, 2. thread lapping tool on said spindle, a piston, means to reciprocate said piston, connections from said piston to said sleeve and spindle to oscillate said sleeve and spindle, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, and means to slowly advance said spindle rotatably during oscillations thereof.

4. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle mounted within said sleeve for rotation on the same axis, a thread lapping tool on said spindle, means to oscillate said sleeve, means to oscillate said spindle and sleeve simultaneously in opposite directions to each other, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, and means to slowly advance said spindle rotatably during oscillations thereof.

5. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle mounted coaxially within said sleeve, a thread lapping tool on said spindle, a piston within said headstock, means to oscillate said sleeve and spindle by reciprocatory movements of said piston, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, means to slowly rotate said piston, and means to slowly advance said spindle rotatably by said rotary movements of said piston.

6. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatable within said sleeve, a thread lapping tool on said spindle, a hydraulically actuated piston, connections between said piston and sleeve and between said piston and spindle whereby reciprocation of said piston will oscillate said sleeve and spindle, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, and supplementary hydraulic means acting on said piston to slowly rotate said piston and advance said spindle rotatably during its oscillations.

7. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatable within said sleeve, a thread lapping tool on said spindle, a hydraulically actuated piston, connections between said piston and sleeve and between said piston and spindle whereby reciprocation of said piston will oscillate said sleeve and spindle, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, rotating means for said piston, and connecting means between said piston and spindle to slowly advance said spindle rotatably during its oscillations.

8. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatable within said sleeve, a thread lapping tool on said spindle, a hy draulically actuated piston, connections between said piston and sleeve and between said piston and spindle whereby reciprocation of said piston will oscillate said sleeve and spindle, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, supplementary hydraulic means to slowly rotate said piston step by step during its reciprocations, and connections from said piston to said spindle to slowly advance said spindle rotatably during its oscillations.

9. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatable within said sleeve, a thread lapping tool on said spindle, a hydraulically actuated piston, gear connections between said piston and sleeve and between said piston and spindle whereby reciprocation of said piston will oscillate said sleeve and spindle, means connecting said sleeve to a holder for the Workpiece being lapped, whereby oscillations of said sleeve will oscillate said workpiece, means to slow- 1y rotate said piston during its reciprocations, and gear connections from said piston to said spindle to slowly advance said spindle rotatably during its oscillations.

10. A lapping device for threaded members comprising a fixed headstock, a sleeve rotatably mounted therein, a spindle rotatably mounted within said sleeve for rotation coaxially therewith, a thread lapping tool on said spindle, a reciprocatory piston within said headstock, a worm gear on said piston meshing with a gear on said spindle, whereby rec-iprocatory movements of said piston will rotate said spindle, means connecting said sleeve to a holder for the workpiece being lapped, whereby oscillations of said sleeve will oscillate said work piece, an annular rack on said piston, gear connections from said rack to said sleeve whereby reciprocations of said piston will oscillate said sleeve, and means to simultaneously rotate and reciprocate said piston.

ALDEN M. DRAKE.

REFERENCES CITED The following references file of this patent:

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